US nuclear agency NNSA hit by cyberattack exploiting Microsoft SharePoint Server flaws.

US nuclear agency NNSA hit by cyberattack exploiting Microsoft SharePoint Server flaws.

The National Nuclear Security Administration (NNSA), a key US agency responsible for maintaining and designing the nation's nuclear weapons, has been breached in a significant cyberattack targeting Microsoft's SharePoint document management software. The attack, which leveraged previously unknown vulnerabilities, has raised concerns about the security of sensitive information and the potential impact on national security.

Microsoft has confirmed that the attack exploited a zero-day vulnerability, a previously unknown flaw that hackers can use to gain unauthorized access to systems. The company has released emergency patches for affected SharePoint servers, but the full extent of the damage is still being assessed [1].

The NNSA, which is responsible for producing and dismantling nuclear arms, as well as responding to radiological emergencies, has reported that a small number of systems were impacted. However, the broader implications of the attack remain uncertain. The US Cybersecurity and Infrastructure Security Agency (CISA) has warned that the impact could be widespread and has recommended that any servers impacted by the exploit should be disconnected from the internet until they are patched [1].

The attack on the NNSA is part of a larger campaign that has targeted numerous organizations worldwide, including government agencies, businesses, and educational institutions. Microsoft has identified two Chinese state-sponsored hacking groups, Linen Typhoon and Violet Typhoon, as well as a third group, Storm-2603, as responsible for exploiting the SharePoint vulnerabilities [2].

The attack highlights the critical importance of maintaining robust cybersecurity measures, particularly for organizations handling sensitive information. As the investigation into the attack continues, it is essential for affected organizations to take immediate action to protect their systems and data. Microsoft has urged customers to apply the latest security updates and to assume that their servers may have already been compromised [3].

References:
[1] https://www.yahoo.com/news/microsoft-releases-urgent-fix-sharepoint-130326084.html
[2] https://www.bloomberg.com/news/articles/2025-07-23/us-nuclear-weapons-agency-breached-in-microsoft-sharepoint-hack
[3] https://americanbazaaronline.com/2025/07/21/microsoft-confirms-sharepoint-server-hack-likely-a-single-actor-thousands-of-firms-at-risk-465323/